Automatic merge from submit-queue (batch tested with PRs 46967, 46992, 43338, 46717, 46672)

Generate protobuf for the audit API

Add protobuf generation & annotations for the advanced auditing API. We're not using them directly now, but settling on the field numbering will help with some 3rd party integrations.

For kubernetes/features#22

/cc @ihmccreery